Not Applicable
Not Applicable
1. Field of the Invention
This invention relates to amelioration of salt build-up in earth under cultivation, and more particularly to distributed apparatus and distributive methods for continual, discrete removal of salts from irrigation water. The invention provides generally small, relatively portable, salt removal devices that are not typically fixed to the ground. These salt removal devices employ a solar distillation system of increased efficiency, and concentrate salts recovered in a readily removable and regenerable vessel. The invention method collects salt-bearing water from a source such as irrigating flows over a cultivated area, solar-distills the water, captures the salt in a solar energy-radiated wick structure and returns the desalted water to the field, all with a multiplicity of quite small devices that suitably fit within and among growing crops without any adverse effect on adjacent plant life.
2. Background Art
Water for agricultural use has historically been made available at low cost, providing little incentive to conserve or efficiently use the water. Typically, as in the United States Southwest, water is applied to the cultivated land in abundance and then drained away by gravity as agricultural runoff back into rivers for use and reuse down stream. Limited amounts of water are not applied and allowed to soak in since excess accumulations of salts from the applied water will remain in the soil, making the field unusable for agricultural use for many crops, i.e. all but the most salt tolerant. The saline content of the used and reused water increases with each use and reuse, and field contact adds even more salts, so that the saline content problem cascades and concatenates as the river water flows to the sea, requiring ever greater flooding to minimize salt accumulation and its effects in the soils being irrigated.
It is an object of the invention, therefore, to provide method and apparatus for the desalination of water. It is a further object to provide in situ desalinization of agricultural water right in the field. A further object is to distribute a plurality of small desalination units over the water flooding the field, each unit acting as a desalinator by taking up saline water and solar distilling it, returning desalinated water to the field, and collecting the salt content in a wick system that can be removed and reconditioned at a remote site so that its saline content is not returned to the rivers and canals used to carry water for irrigation. A preferred object is to provide a hand-carryable unit that can be floated on the agricultural water, and, using a reflector such as a primary mirror and secondary mirror that concentrates the incident solar radiation on the upper end of a wick that has its lower end immersed in the field water, effect in situ desalinization. Other objects will appear hereinafter.
The objects of the invention are realized in an in situ desalinating system comprising a multiplicity of distributively arranged individual desalinating units for continually removing saline content from field surface water, the units being floatable on the field surface water, each unit comprising a wicking structure including a wick having a lower end portion immersed in the field water and an upper end portion, a solar energy collection structure circumjacent the wick upper end portion including a primary mirror adapted to collect incident solar energy and redirect it to the upper end portion of the wick in wick-contained water evaporating relation, and an evaporated water collector arranged to condense evaporated water in saline content-free relation and return the condensed water to the field water.
In this and like embodiments, typically, the wicking structure comprises a bracket arranged to support the wick within the unit, the primary mirror being supported by the bracket, the water collector comprises a light-passing transparent or translucent dome opposing the primary mirror and adapted to pass incident solar radiation to the primary mirror, and there is further included a secondary reflector or mirror enclosed by the dome and arranged to redirect solar energy reflected upward by the primary mirror onto the wick upper end portion, the dome defines a condensed water flow paths from the dome to the field water, the wick is removable from the bracket and returnable thereto in saline content-cleansed relation, the solar collection structure includes a lens opposite the primary mirror, which lens reemits all angles of incident light from the lens primarily normal to the lens such that the solar collection structure lens is a source of lambertian light within the dome.
In a further embodiment, the invention provides an in situ desalinating system comprising a multiplicity of hand-carryable, distributively arranged individual desalinating units for continually removing saline content from field surface water, the units being floatable on the field surface water, each unit comprising a wicking structure including a wick having a lower end portion immersed in the field water and an upper end portion out of the field water, a solar energy collection structure circumjacent the wick upper end portion including a lens and primary mirror system adapted to collect incident solar energy and redirect it to the upper end portion of the wick in wick-contained water evaporating relation, and an evaporated water collector including a cover above the wick upper end portion arranged to condense evaporated water in saline content-free relation and return the condensed water to the field water circumjacently of the wick, the cover defining the solar collection lens.
In this and like embodiments, typically, the wicking structure comprises a bracket arranged to support the wick vertically disposed within the unit, the primary mirror comprises a spherical or parabolic reflector supported by the bracket, the water collector comprises a light-passing transparent or translucent dome defining the solar collection structure lens, the dome opposing the primary mirror and adapted to pass incident solar radiation thereto, and a secondary mirror arranged within the dome to redirect solar energy reflected upward by the primary mirror onto the wick upper end portion, the dome defines condensed water flow paths from the dome past the primary mirror and to the field water, the wick is demountable from the bracket and remountable thereto in saline content-cleansed relation, the dome-defined solar collection structure lens reemits all angles of incident light from the lens primarily normal to the lens, and the solar collection structure lens is a source of lambertian light within the dome.
In another embodiment, there is provided an in situ desalinating system comprising a desalinating unit for continually removing saline content from field surface-disposed saline water, the unit being floatable on field surface water and comprising a housing having a solar heat energy-passing, water-impervious wall defining a generally closed chamber having a lower portion adapted for contact with the saline field surface water and an upper portion generally out of contact with the field water, a saline water collection structure within the chamber supported by the housing for saline water immersion, reflector structure arranged to concentrate solar heat energy passed into the housing and to direct the concentrated energy to the collection structure for heating saline water collected in the collection structure to temperatures increasing the rate of water evaporation, the evaporated water being condensed within the chamber upper portion for return to the field surface water, the housing defining a condensed water return path to the field surface water, whereby saline water is returned to the field surface water with lowered saline content in field surface water saline content-ameliorating relation.
In this and like embodiments, typically, the chamber upper portion comprises a translucent material having a downwardly open shape arranged on the chamber lower portion to oppose the field surface water, the translucent material is a sandblasted, pattern-molded, or otherwise roughened surface to be light diffusing and is arranged to reemit all kinds of incident light primarily normal to the material shape, i.e. the translucent material functions as a source of lambertian light.
Further, in this embodiment, typically, the unit is hand-carryable and in water-free condition weigh less than about 10 pounds, the unit has a height of less than about 18 inches, and a width of less than about 18 inches, the water collection structure comprises a wick and a wick support mounted within the lower portion of the chamber, the wick comprises a fibrous member adapted to wicking water vertically from an immersed end upward, and the fibrous member is impervious to corrosion from salt.
In yet another embodiment, there is provided an in situ desalinating system comprising a multiplicity of hand-carryable, distributively arranged individual desalinating units for continually removing saline content from field surface water, the units being floatable on the field surface water, each unit comprising within a chamber a wicking structure including a wick support and a wick supported by the wick support in extended relation, the wick having a lower end portion immersed in the field water and an upper end portion out of the field water, a solar energy collection structure circumjacent the wick upper end portion including a lens and mirror system adapted to collect incident solar energy and redirect it to the upper end portion of the wick in wick-contained water evaporating relation, and an evaporated water collector including a cover above the wick upper end portion arranged to condense evaporated water in saline content-free relation and return the condensed water to the field water circumjacently of the wick.
Typically in this and like embodiments, the wick support comprises a bracket extended along the wick in supporting relation, the bracket exposing the wick within the chamber in concentrated solar heat energy-receiving relation, the chamber has a wall defining the lens, the lens comprises a lambertian light source, the chamber has a lower portion and the solar energy collection structure further includes a reflector structure comprising a primary mirror in the form of a mirrored web extending transversely across the chamber lower portion in spaced relation to the field surface water and a secondary mirror opposite the web for redirecting reflected solar radiation from the web onto the wick upper end, the web defining the wick support bracket.
In this and like embodiments, typically, the web has an upward facing mirrored surface that defines a parabolic or spherical primary mirror arranged to concentrate solar heat energy passing into the housing onto the mirror, the secondary mirror being opposite to and spaced above the wick upper end and arranged to reflect solar energy onto the wick, the bracket is disposed centrally of the chamber, the web extending radially thereof, whereby the wick is surrounded by the spherical or parabolic primary mirror, the primary and secondary mirrors being relatively arranged to concentrate solar heat energy onto exposed portions of the wick upper end in the bracket.
In a highly particular embodiment, there is provided an in situ desalinating system comprising a multiplicity of distributively arranged individual desalinating units for continually removing saline content from field surface disposed saline water, the units being hand-carryable and floatable on field surface water and comprising a housing having a solar heat energy-passing, water-impervious translucent plastic wall defining a generally closed chamber having a generally cylindrical lower portion adapted for contact with the saline field surface water and a parabolically shaped upper portion, a light energy collection and redirection structure comprising a primary mirror/reflector-defining web disposed transversely of the housing and an opposing secondary mirror above the primary mirror arranged to direct incident solar energy to a predetermined locus, the web having a central opening, a saline water collection structure comprising a fibrous wick having an upper end and a lower end and sized to be supported in the web opening, the web carrying the wick with its lower end arranged for immersion in saline field water and its upper end at the predetermined locus for heating saline water collected in the collection structure to temperatures at which the rate of water evaporation is increased, the evaporated water being condensed against the chamber upper portion for return along the wall to the field surface water, the housing lower portion and the web defining a condensed water return path to the field surface water, whereby saline water is returned to the field surface water with lowered saline content in field surface water saline content-ameliorating relation.
In this and like embodiments, again, typically, the wall defining the chamber upper portion is light-diffusing and provides lambertian light within the chamber upper portion.
The invention further provides a method of desalinating agricultural water in a field, including disposing a plurality of desalinating units upon the field water, maintaining in each unit a wicking structure including a wick lower end immersed in the water and an upper end in wicking communication with the wick lower end, providing a lens and mirror system including a primary mirror in each unit adapted to reflect solar radiation incident upon the unit onto the wick upper end, evaporating from the wick upper end solar distilled water, and returning the solardistilled water to the field water while retaining the saline content of the water in the wick. The method further contemplates separating the wick from the wicking structure, cleansing the wick of accumulated salts, and reusing the wick to collect saline content from the field water, floating the units upon the field water, and maintaining a translucent cover above the wick upper end, and condensing the evaporated water on the underside of the cover, the cover being shaped to return the condensed water to the field water away from the wick.